Range control system



Dec. 3,1935.

H. M BIEBEI.A

RANGE CGNTROL SYSTEM Filed Feb. 8, 1955 2 Sheets-Sheet l INVENTOR Herma/7 M B/@be/ A'TTORNE Dec.3, 1935. H. M BIEBEL RANGE CONTROL SYSTEM Filed Feb. 8, 1935 2 Sheets-Sheet 2 Fig, 6

INVENTOR Hrman M. B/'ebe/ ATTORNE Cil Patented Dec. 3, 19.35

PATENT .OFFICE 2,oz",1'19 RANGE oo N'rnor.l SYSTEM Herman M.

Westinghouse Electric Biebel, Oakmont, Pa., assignor to & Manufacturing Company, East Plttsburgh, Pa., a corporation of Pennsylvania' Application February s, 1935, serial No.`5,593 momma (ci. 21a-zo) 1 My invention relates to cooking devices and more particularly to temperature control systems for rangeovens.

An object of my invention is to provide a relatively simple and easily installed and operated thermostaticr means for obtaining a predetermined temperature cycle ina range oven.

. Another object of my invention is to provide a. Single thermally actuable switch controlling a source of heat inl a cooking deviceysuch as a range oven, to obtain a short-time peak temperature and then a lower maintained average temperature in a cooking chamber. 'y

Other objects of my invention will eitherbe pointed out specifically in the course of the following descr'ption of one form of system embodying my invention, or will be apparent from y such description.

Inpracticingmy invention oI provide, in combination with a range oven enclosing a cooking chamber, a single quick-acting thermostatic switch adapted to change its operating temperature after the rst operation thereof, to control a heating element associated with lthe cooking chamber to obtain a short time peak temperature and then a lower maintained average temperature in the cooking chamber. I also provide for varyingthe operating temperatures of the thermostatic switch" assembly constituting a vpart of my System. a f

It lis well known that the proper cooking of a roast of meat involves iirst raising the temperature in the cooking chamberA to a value on the order of 550 F. to sear the outside surface of the Tmeat, to seal the juices therein, and to thereafter cook the meat by subjecting it to a maintained lower average temperature for a predetermined length of timev until it has been cooked to the desired degree. v

' In a range of the kind now in use and heated either electrically or by gas, and provided with automatic thermally-actuable means for controlling the temperature in the cooking chamber, the operator will adjust the thermostatic device to so control the heat sourcethat the initial temperature will be the desired searing temperature, which as noted above, may be 550 and will be maintained for a short period of time, and will then change the setting of the thermostatic def vice to cause Y which may be on the order of vsay 350 to 400F.

it to operate at a lower temperature.

Several different combinations of thermostatic' switches to obtain the desired so-called dual cycle temperature control have-been' suggested but these usually require a plurality. of such there is located a'sheet or and terminal members 21 nal members h'einbefore lbridging members 1ends oi' contacts i1 adapted to engage bers Il! and 2|, while switches, whereas my present system employs a Single thermally-actuable switch controlling a .heat oSource Oeither directly or indirectly, and l whichis adapted to automatically vary its operating temperature after ithasonce been actu- 5 ated tol deenergize the heat source.

In the accompanying drawings;

Figure 1 is a top plan view of a thermostatic switch used in the system embodying my invention, o v 10 Fig. 2 is a view in section therethrougntaken on the line II-II of Fig. 1,

Fig. 3 is a view in section through the device shown'in Fig. 1, taken on the line III-III thereof and Showing the thermal position, o

',Fig. 4 is a top plan view of a modined form oi' Y thermal Jswitch which I may luse in the systemk embodying my invention,

Fig. 5 iS a view in lateral section taken on the 20 line V--V therethrough showing the bimetal element in its open position, and

Fig. 6 i's a schematic view showing the thermal switch illustrated in Figs. 4 an'd 5 of the drawings as utilized to controlan electric heater in a range oven. Referring first to Figs. 1, 2 and 3 of the drawings, I have there illustrated a thermostatic switch assembly il which includes a base i3 of Substantially circular shape and which may be made lof metal. Adjacent to one face thereof disk l5 of electricmica. A pair f xed and i9 and a pair insulating material such as strip-type contact members I1' of similar iixed contact-and-terminal niembers 2| and 23 are arranged in general triangularrelation against the outer face of sheet I5, being held thereagainst either by rivets 2l as used for the nat contact members or by combined rivet and 23.

A snap-acting bimetal disb 2l which is erably of the reversible dished type disclosed claimed in Patent 1,448,240 to J. A. Spencer, is associated described. It is provided with` three insulatedly-Xmounted contact I Il (only two being shown), one of which is adapted to engage the acent and I9, the second o which 50 the adjacent ends of memthel third/contact bridging member is adapted to engage the adjacent ends of members l'I-an'd'l.

' Means' for supporting the dat :a cenmiciy 5t element in its open 15.

for the members 2| 40 with the baseandr contact and termi- 'I i plate 6I which is thereof is shown as comprising a studtl, the is 29 being mounted loosely thereon adjacent one reduced-diameter end thereof and held thereon as by a small washer 35 against which the reduced outer end portion oi the stud 33 is hammered over. The stud 33 is provided further with an integral annular shoulder 31 intermediate its ends, for a purpose to be described, and is so designed and constructed as to slide freely longitudinally of its length within an opening 39 in the base I3. A first nut 4I having an annular end'portion 43 thereon is screw threaded on the other end of stud 33 and is held by lock nut 45 in a manner well known in the art.

,The disk 29, when in the one dished position shown in Fig. 2 of the drawings where the above described contact bridging members are in engagement with the fixed contact members, will exert a pull onl the stud 33 tending to move it downwardly, as seen in Fig. 2 of the drawings, and it is to be noted that there will be a small 'clearance between the upper face of the annularflange 31 and the adjacent lower face of base I3.

When the disk 29 is subjected to a predetermined high temperature, which for, illustrative purposes may bel assumed to be 550, it will move to its oppositely dished position as shown more particularly in Fig. 3 of the drawings, the amount of reverse di'shing being limited by three stop pins 41 having screw threaded engagement with the base I3 and extending through openings in the disk adjacent to its periphery. The force exerted by disk 29 on the stud 33 will now be in an opposite direction and will tend to move it upwardly, as seen in Fig. 3 of the drawings-so that the upper face of shoulder 31 will be in engagement with the lower face of base I3. In order to in sure that there will be no movement of the stud 33 until desired, I provide a helical spring 49 around the stud`33 between the/base I3 and a flange 5I on the stud.

Means for retaining the stud 33`in its second or open position described above comprises a pair of wedge members 53 and 55, generally of bar attrarre While thethermo'static switch illustrated generally in. Fig. 6 of the drawings is that shown in Figs. 4 and 5 of the drawings, the same explanation will hold and itis, therefore, to be assumed that the thermostatic switch of the drawings has been replaced by switch Il. It is to be further understood that a main switch for manually controlling the energization of the heating element 13 is providedf'and that any other desired control device such as a time clock may be provided, but since these constitute no essential part of my invention they have not been illustrated.

Let it be assumed that the operator desires to cook a roast of meat in the oven chamber 11 and l5 has closed the main circuit controlling switchv (not shown). As shown in Fig. 6, the thermovstatic device II or 1511s suitably supported in direct heat receiving position in the 4.cooking chamber 11 so that it will follow closely any tem- 20 perature variations therein caused by the source of heatu. Let it be further assumed that the design and construction of the thermostatic switch II and particularly of the disk 29 is such shape and each having a recessed end indicated by 31 in Fig. 1 of the drawings, the other ends of the two bars being pivotally mounted as at 59 on a suitably secured against the upper face of base bolts 63. The two wedge arms are urged together by a helical'spring 65, the ends of which are secured to intermediate. portions of the respective wedge arms 53 and 55. Normally, tbe recessed edge portions of wedge arms 53"and 55 I3 as by a plurality of smally will engage the annulus 43 of the rst nut 4I when the stud l33 is in the position shown in Fig. 2 of. the drawings. However, when the stud has been vmoved to the upper position shown in Fig. 3

of the drawings the wedges 53-and 55 are permitted to move under the annular shoulder 43 or between its lower face and the upper face of base i3, being urged into such position by the spring 35.

Means for forcing the wedge ends out from l their original positions as shown in Fig. l ofi the drawings may comprise a pivotally mounted cam member 31 of oval shape actuabie by an arm 5S which is pivotally mounted in plate 3l.

The operation of this device may be described brieiiy as follows, having reference also to. Fig. 6 oi the drawings wherein I have illustrated a ling the heat source that when in the position shown in Fig. 2 of the 25 drawings and with the heat source suitably energized to raise the temperature in the oven, it will move with a sudden action to its nopenposition, as shown in Fig. 3 of the drawings, vand that this operation will occur at a. temperature 30 of say 550 F. This temperature is selected since it has been foundy to be a suitable temperature to cause searing of the outside surface of a roast of meat.

As has already been stated, when the disk 29 35 snaps to its second or open position, 'the outer portions thereof through which thestop pins 41. extend will engage thev stop pins, as' shown in Fig. 3 of thedrawings, and cause the stud 33 to move upwardly, as seen in Fig. 3 ofthe draw'- 40 ings, thereby permitting the spring-biased wedge ends of members 53 and 55 to move under the annulus 43 to thereby hold the stud and, consequently, the disk in a new'position where the reverse dishing o' the disk 29 is not as great as it was originally and as shown in Fig. 2 of the drawings. The stud 33 is now held substantially lxedor rigid in the position shown in Fig. 3 of the drawings, and it may be assumed for illustrative purposes that the disk 29 will move to 50 its closed position'at a temperature of say 350 F. Since the dish of the disk is less or, to state in other words, its radius of 'curvature is greater, it will open at a lower temperature than before, which temperature may, for illustrative purposes,` 55 be considered to be 400 F. Thus, the :drst opening movement of disk 23 resulted in deenergiz- 13, the nrst reclosingthereof resulted in reenergizing the heat source I3 at a temperature of 35,0 F., while the second opening of the disk will be effected at about 400 F., the disk thereafter closing, and opening the circuit of 'the heating, element at those temperatures as range oven structure 1l adapted tobe heated by an electric resistor 13, both the oven structure and the vheater being shown schematically.

long as fmay .be desired by temperature cycle obtainable is, therefore, that of a short time maximum or peak temperature, on the order of 550, a reduction of the chamber temperature to a value on 'the order of 350 and a reopening of the thermostatic switch at say I400" with alternate reclosing and reopening of the circuit of the heat source to thereby maintain anaverageoi say 375. The device illustrated in Figs. l, 2 and 3 of the drawings, therefore, constitutes a single thermostatic switch comprising a part of a temperature an operator. The

15 shown in Fig. 6" 5 y control system for a cooking chamber, which system is eifective to operate to provide a shorttime peaky temperature in this cooking chamber and thereafter a lower maintained averagel temperature inQ the cooking chamber for as long asv may be desired by the operator oras determined by other elements usually utilized in range ovens, such as a time clock. It is to be noted that the 'thermostatic switch constituting, a part of the system embodying my invention utilizes the reactive effect of a snap-acting disk when moving from its initial closed position to its open position, and thereafter operating at new upper temperature limits and at the sgae lower temperature limit to interrupt and r lose the energizing circuit.

When it is desired to be 'able to vary the operating values both of the peak temperature and of the maintained lower temperature, I may use the structure shown in Figs. 4 and 5 of the drawings. A base 8|, which is .substantially the same as base I3 and has a disk Il of electric-insulating material such as mica mouted thereon, tiogether with substantially the same fixed contactv terminals and 'terminal members I1, i9, 2| and 2l, has operatively'associated therewith a snapacting -bimetal disc 29 lwhich is mounted onva stud in substantially the same manner as the` disk 29 wasdescribed as being mounted on the end of stud 33. The stud l5 is provided with ex- J ternal screw threads and interflts with a movable hollow or tubular stud 81, which stud l1 is the counterpart of axially movable stud Il hereinbefore described. Stud 5l is provided with an integrali collar or flange 85 intermediate its ends and has a. iirst or inner nut 9| and a lock nut 93 at its upper end which are the counterpart of nuts 4| and 45 in the'device shown in Figs. 1, 2 and 3 of the drawings. Stop pins Q1 are provided, preferably three in number, as was hereinbefore described. a The tubular stud B'l is adapted to move axially in an opening 95 in base Il and is prevented from peripheral movement relatively thereto as by `a pin 91 therein moving in an axial groove 9! in base 8|. A spring |0| is provided around the tubular stud 81 between iiange |03 on the lower end of stud 81 and the lower face of hase 5|.

Substantially the same wedge arms 53 and 55, helical spring l5 and the porting the ends of arms 53 and 55 are provided, as well as the cam member 51 and arm 59, as were hereinbefore described in connection with the device shown in Figs. 1 and 2. The upper end of rod or stud 85 is provided with a manuallyactuable adjusting arm |05 so that an operator` may initially adjust the position loi' the central part of the disk 25 to any desired value andit is to be understood that a mutable scale (not shown in the drawings) may be provided on the outside of the oven structure 1| so that an operator may be aware of the operating temperature of the adjusted thermostatic switch 15.

As has already been set forth, the greater the initial dishing or the disk n, the higher wui be its opening temperature. Therefore, if the operplate 5| pivotally' supy ator adjusts arm |55 and supporting rod I5 in such manner as to decrease the amount of dish of the bimetal disk 29 when the switch is in its closed position, the lower will be the upper temperature' at which the'disk snaps to its open position, as shown in Fig. 5 of the drawings. On the other hand, ii' he `\so moves arm |05 as to increase the initial dishing of the disk, the higher will be the initial temperature at which the circuit oi' the heat source is opened. The same comments hold with regard to the upper and the lower operating temperatures @of the disk in its adjusted position, that is, when the tubular stud 8l has been moved to the position shown in Fig. 5 of the drawings. K1t being evident that an operator may adjust the position of the central -portionA of the disk relatively to the tubular stud 81 by turning atuating arm ',|||5.

The system embodying my invention and comprising a single thermostatic switch so designed and constructed as to provide diilerent operating values of the switch automatically and by the reactive eilect i the iirst operation of a snapacting bimetal element, thus provides a single `control element operable to obtain an adjustable peak temperature in a cooking chamber and to. thereafter obtain a lower maintained adjustable average temperature in the cooking chamber as may be desired or -required for the cooking oi' different kinds of food.

It is, of course, Vobvious that if the operator permits the wedges to remain in the position to which they are moved after the nrst operation of the bimetal element, no peak temperature will be obtained but that only a desired adjustable lower maintained average temperature is obtainable.

It is further obvious thatthe system embodying my invention is not dependent upon the particular form of snap acting bimetal element-or wedging means, but that it may be practiced with any` other form of snap-acting thermally actuable element or wedging mechanism, or the equivalent.` Hence, I desire it to be understood that I do not desire to be limited to the particular details of `ture and then a lower maintained average temperature in the cooking chamber, said means comprising a pair of relatively movable cooperating contact members Ain circuit with the heating element,A a snap-acting bimetallic device supporting and actuating one of said contact iiiembers, means operatively associated with the blmetal device to initially govern the heating element to interrupt its circuit at a predetermined'.V

peak temperature and means automatically set in operation when the bimetal device moves to its interrupting position to 'change the adjustment to cause the bimetal device thereafter tol operate to maintain a liwer average temperature value i in the cooking chamber.

2. In combination with a cooking device including a cooking chamber and a source of heat therefor, means for controlling the source of heat to obtain a short'time peak temperature and then a 'lower maintained temperature in the cooking chamber, said means comprising a pair of rela- 'tively movable. cooperating contacts controlling the energization of the heat source, a bimetal elei spcnsive to chamber ment actuating one of 'said contacts in accordance with temperature variations in the cooking chamber, means operatively associated withthe bimetal element to initially support the same to effect disengagment of the cooperating contacts at a predetermined peak temperature, and means automatically operable by the opening movement of the birnetal element to change its condition to thereafter operate to effect sequential disengagement of the contact members at a lower temperature value.

E. in combination with a cooking device including cooking chamber and a source oi heat therefor, means for controlling the source ci heat to obtain a short time peak temperature and then lower maintained temperature in the cooking chamber, said means comprising a base, relatively movable cooperating contact members at least one oi which is supported by said base and controlling the energization oi the heat source, a quick-acting binietal element actuating one of the contact members in accordance with temperature variations in the cooking chamber,

means supporting the bimetal element from the' base initially in a position to cause it to move to open position at a certain peak temperature, and automatic means operable upon opening move-- ment of the bimetal element to hold the supporting means in a second position relatively to the ,base to cause it to eiect engagement of the cooperating contact members at a lower temperature thereafter,

4. Incombination with a cooking device including a cooking chamber and a source of heat therefor, means for controlling the source of heat to obtain a short time peak temperature and then a lower maintained average temperature in the cookingchamber, said means comprising a base, a pair of contacts controlling the energization oi the heat source, a thermostatic element movable from one to another of two operative positions with a snap action and acting one of the contacts, means supporting the thermostatic element from the base, said means being movable relatively to the baseand held in a position by the thermostatic element to effect disengagement of the contact members at a peak temperature, and means rendered effective upon the first dis-engaging movement of the thermostatic element to vvary the position of the supporting means to cause thev thermostatic element to sequentially disengage the contact members at a lower temperature.

5. In combination with a cooking device including a cooking chamber and an electric heater therefor, means for controlling the heater to obtain a short time peak temperature and then a lower maintained average temperature in the cooking chamber, said means including a pair of cooperating contacts controlling the energzation of the heater, a bimetal element retemperature having two opposed operative positions and actuating one of the bimetal element tacts at a peak temperature and means set in operation by the reactive edect of the bimetai element upon effecting disengagement of the contact members the iirst time to cause the support to move the bimetal element to eiect disengagement of the contacts at a lower temperaturen acaairo 6. In combination with a cooking device including a cooking chamber and an electric heater therefor, means for controlling the heater to obtain a shortJ time peak temperature and then a lower maintained average temperature in 5 the cooking chamber, said means including a single thermally-actuable switch controlling the energization of the heater and operable to doen- .ergize the heater at a predetermined peak ternperature, said switch including means set in oplo eration by the first opening movement thereof to cause it to operate to decnergize the heater thereafter at a lower temperature. 7, in combination' with a cooking device including a cooking chamber and an electricl heater therefor,- means for controlling the heater to obtain -a short time peak temperatureand then a lower maintained average temperature in the cooking chamber, -said means including a single thermally-actuable switch responsive to chamber temperature controlling the energizetion of the heater and initially operative `at a predetermined peak temperature to open the heater circuit and to reclose the heater circuit at a predetermined low temperature, said switch comprising means set in operation by the first opening movement thereof to cause it thereafter to operate at a lower opening temperature and the same closing temperature to maintain a lower average temperatureI in the cooking chainber.

8. In combination with a cooking device including a cooking chamber and an electric heater therefor, means for controlling` the heater to obtain a short time peak temperature and then a lower maintained average temperature in the cooking chamber, said means including a single thermally-actuable switch controlling the ener- .gization of the heater and operable to deenergize the heater at a predetermined peak temperature, said switch including wedging means set in operation by the first opening movement; of the switch to cause it to operate to deenergize the heater thereafter at a lower temperature.

9. The system as set forth in claim 7 in which 45 the switch includes relatively movable supporting members and the means set in operation by the first opening movement includes a wedging means cooperating with a relatively movable supporting mea-ns to hold them in different relative positions after the rst operation of the switch.

10. In combination with a cooking device including a cooking chamber and an electric heating element therefor, means for controlling the Y heating element to obtain a short time peak temperature and then a lower maintained average temperature in the cooking chamber, said means comprising a pair of relatively movable cooperating contact members in circuit with the heating element, a thermostatic device supporting and actuating one of said contact members, means operatively associated with the thermostatic device to initially govern the heating element to interrupt its circuit at a predetermined peak temperature and means automatically set in operation when the thermostaticdevice moves to its interrupting position to change the adjustment to cause the thermostatic device thereafter to operate to maintain a' lower average 70 temperature value in the cooking chamber.

,- HERMANlVI. BIEBEL. 

